Group Image of Attributes Panel is intended for editing of image and its parameters.

With the help of button in the line Image you can choose image from BMP, JPEG (JPG), GIF, PNG, PCX, PSD, ICO - files and Windows Metafiles.
At that you can see original image sizes in the line Image and in spinedits Width and Height.
To change size of your image use the button in the line Width.
Checked flag Transparent sets transparent image color as the color of the lower left pixel (except GIF- image that has its own rules for transparency).